Merge branch '2.7' into 2.8

Author: wouterj

components/asset/introduction.rst

@@ -8,6 +8,9 @@ The Asset Component
    The Asset component manages URL generation and versioning of web assets such
    as CSS stylesheets, JavaScript files and image files.
 
+.. versionadded:: 2.7
+    The Asset component was introduced in Symfony 2.7.
+
 In the past, it was common for web applications to hardcode URLs of web assets.
 For example: